MATLAB: Triggering a slave target with parallel port

masterparallel portSimulink Real-Timeslavesyncronizationtriggerxpc target

Hi, I need to syncronize two targets running xPC Target. I use a Master/Slave approach. I read I have to set the slave model to run on IRQ7 (coming from parallel port) instead of using the Real Time Clock of the machine.

I correctly did this but…how can I send the clock signal from the master target? I read I need to send a square waveform on pin 10 of the parallel port in order to generate the interrupt on the slave. But I am only able to find blocks writing on data pins (1-8) and control pins of the parallel port. Pin 10 is a status pin, how can I write on this pin from the master target?

Thanks

Best Answer

To confirm: you need to send your square wave on the nACK pin? You cannot do that: ACK is input only.

Bit 4 of the control port (see page 7 of http://retired.beyondlogic.org/spp/parallel.pdf) enables the host to generate an IRQ when an edge is seen on the nACK pin; see page 12 of that document.

Does your slave need an edge to trigger a particular action, or does it need a full clock? If it needs an edge then you could potentially use the strobe (pin 1) or nSelect (pin 17). If it needs a full clock then you have a problem as parallel ports are not designed for shared clocks: they are designed for asynch work with multiple inputs per asynch cycle.

Clock sync is better done with an D/A convertor that offers a shared clock. Or, I suppose, perhaps one of the old BISYNC connectors (if you can still find one.)

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MATLAB: How to configure a GPIO pin as an external interrupt in a Target Support Package

The attached model configures GPIO0 as external interrupt to trigger the blinking of LED. The custom code in the System Initialize block assigns GPIO0 as an input to trigger the XINT1 interrupt:

EALLOW;                                        
GpioCtrlRegs.GPAMUX1.bit.GPIO0 = 0;            
GpioIntRegs.GPIOXINT1SEL.bit.GPIOSEL = 0;      
EDIS;                                          
XIntruptRegs.XINT1CR.bit.ENABLE = 1;           
XIntruptRegs.XINT1CR.bit.POLARITY = 1;

The ISR toggles the LED based on a rising edge of GPIO00. Connect GPIO to 3V and GND in order to blink the LED.

MATLAB: How to use a single General Standards PCI-ADADIO card with an external trigger in Burst Scan mode with xPC Target 3.2 (R2007a)

This is possible, but it will take some effort to do it with xPC Target 3.2 (R2007a). The ADADIO doesn't give an interrupt for a programmable number of samples, but only for half a hardware FIFO full of samples. For this reason, it is never allowed this board to be used in frame mode. Frame mode would give you a buffer completion interrupt. Here it sounds like your frame size would be 1 sample.

If you simply don't use the ADSTART block, then an external pulse can be used to start an acquisition. Unfortunately, it really isn't that simple since you would then wait at the ADREAD block until the external pulse came in. If the model execution and external pulse timing aren't exactly synchronized, you might get an execution overload when the ADREAD finally returns.

So, how do you synchronize model execution with an external pulse? The easiest way is to use the parallel port interrupt. You feed your pulse to both the ACK pin on the parallel port and to the external clock or trigger input on the ADADIO board. You will need to pay attention to which clock edge causes each action. A rising edge on the parallel port causes an interrupt, but it is not clear which edge starts the ADADIO. You should check the manual for that information.

You could also improve this with external logic to delay the parallel port interrupt until your burst time after the trigger pulse, but that is up to you.

The ADREAD block only knows how to read 1 sample from each channel it is configured with so that is your maximum burst size. If you want a frame of data from each channel, you would have to modify the block. However, there are currently no plans to do that for this board.

Best Answer

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MATLAB: How to configure a GPIO pin as an external interrupt in a Target Support Package

MATLAB: How to use a single General Standards PCI-ADADIO card with an external trigger in Burst Scan mode with xPC Target 3.2 (R2007a)

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